a bunch of people give me different bits and incomplete bits of information

That's where experience and willingness to learn and filter come in helpful.

What "other forum" ?

"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.Do not send technical questions via personal messaging - they will be ignored.I speak for myself, not Arduino.

have you learned about a single led and resistor yet? then take that and span it over 300 led's, your going to encounter more problems along the way but we can address them as they come up. You got to take some initiative and figure some of this out instead of carrying on this idea that someone is going to personally devote their life to hold you by the hand in every single moment of your project.

"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.Do not send technical questions via personal messaging - they will be ignored.I speak for myself, not Arduino.

I'd suggest starting with 1, get the resistance values figured out for your particular RGB LED, get some basic code to work to understand the datasequence needed, then build up from there.To multiplex, you will need banks of PNP transistors or P-channel MOSFETs to control the voltage to the parallel'ed LEDs.What kind of architeture were you thinking? 'x' banks of 'y' LEDs using 'z' WS2803s?